Utility locators (also denoted as “buried object locators”, “utility locators”, “buried utility locators”, or “locators”) are devices for sensing magnetic fields emitted from hidden or buried utilities (e.g., underground utilities such as pipes, conduits, or cables) or other conductors, and processing the received signals to determine information about the conductors and the associated underground environment. Traditional utility locators and associated systems used in locate operations (also denoted herein as a “locate”) are tuned to receive magnetic field signals generated from the utility or other conductor through currents flowing in the utility. These currents may be coupled, either directly, inductively, or capacitively, from a signal transmitter device (also denoted herein as “transmitter”) specifically designed for such tasks or may be currents intended to flow in the conductor, such as power grid currents for providing power to homes or businesses.
In some locate operations, such as with blind pipeline surveys, it may be difficult and/or impractical to position a transmitter to effectively couple signals to a conductive buried utility line using a typical transmitter. Though the use of a transmitter may, in some cases, be used to locate certain utilities, the reliance upon a transmitter in a utility locating operation may not effectively inform the user of the absence of utilities within the ground where the transmitter has failed to couple signal onto the utility. Furthermore, locator devices and systems as known in the art fail to take advantage of other signal information which may be passively available within the locate environment beyond those signals intentionally generated by a transmitter. Existing utility locators and associated systems that utilize passive signals for the purpose of locating buried utility lines are greatly limited in number and selection of tunable passive frequencies, typically only using 50 Hz or 60 Hz powerline frequencies or associated harmonics.
Accordingly, there is a need in the art to address the above-described as well as other problems.